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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug gcov-profile/112717] .gcda profiles compatibility guarantees
 between GCC versions
Date: Mon, 27 Nov 2023 00:44:12 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112717

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I thought this was documented but I don't see. There is no guarantee for
forward or backwards compatibility at all. In fact iirc there is a version
stored in the files to make sure the correct version is used with the versi=
on
of tools/compiler.

Plus not only different versions of the compiler changes profile data but a=
lso
different preprocessed sources could change the profile data (that even mea=
ns
compiler options which change macros, e.g. -D* and even some -f/-m options
define some macros that could change the sources being processed).=